Electronic circuitry, particularly in radio frequency (RF) applications, frequently employs inductive components. Such components are generally bulkier and more susceptible to damage and misalignment during installation and use than similar capacitive and resistive components. As a result, there is a tendency to design around the need for inductive components even in those circumstances where the inductive component provides the most direct solution to a particular circuit problem. Such non-inductive circuit designs have less than optimum operating characteristics.
Another common technique to reduce the required number of inductive components is to tap an inductor at one or more points along its length to thereby serve functions that would otherwise be fulfilled by a plurality of inductors. Inductive components utilized in this fashion are normally wound on cylindrical or toridal coil forms. The tapped connections are made at appropriate points along the axial extent of the inductor. However, points at which each connection is made to obtain the precise turns ratio desired cannot be easily determined. Therefore, there may be significant differences in successive tapped sections of the coil, to result in a variation in the electrical parameters, such as a phase shift, of a signal passed through the tapped coil. Similarly, the assembly process and in service use of the coil may physically distort the coil changing the operating characteristics. Such changes can require laborous set-up inspection in assembly and frequent service in use.
Therefore, it is desirable to have a coil inductor for electronic circuits that may be easily configured to have any selected inductance and number of tap points and particularly where such a coil resists physical distortion and therefore cause a predictable phase shift effect in a processed signal.